Apparatus for controlling the tension in a strip advancing continuously in a strip processing line



s. o. PERRINE 3,227,347

G THE TENSION IN A STRIP ADVANCING Jan. 4, 1966 APPARATUS FOR CONTROLLIN CONTINUOUSLY IN A STRIP PROCESSING LINE Filed March 31, 1964 2 Sheets-Sheet 1 INVENTOR Sterling 0. Perrine Jan. 4, 1966 s. o. PERRINE 3,227,347

APPARATUS FOR CONTROLLING THE TENSION IN A STRIP ADVANCING CONTINUOUSLY IN A STRIP PROCESSING LINE Filed March 51, 1964 2 Sheets-Sheet 2 INVENTOR E! Sterling 0. Perrine United States Patent M 3,227,347 APPARATUS FOR CONTROLLING THE TENSION IN A STRIP ADVANCING CONTINUOUSLY IN A. STRIP PROCESSING LINE Sterling 0. Perrine, Warren, Ohio, assignor to The Wean Engineering Company, Inc., Warren, Ohio, a corporation of ()hio Filed Mar. 31, 1964, Ser. No. 356,133 8 Claims. (Cl. 226195) This invention relates to apparatus for controlling the tension in a strip advancing continuously in a strip processing line. In modern high speed processing lines which perform work on a strip of material advancing continuously in the line accurate control of the tension in the strip throughout the line is important. This is true of steel strip processing lines. The strip passing through such a line may be very thin and may advance at high speed, for example 4,000 feet per minute. Under such conditions irregularities in strip tension can cause irregular strip tracking, undue wear on machinery and strip breakage.

Fluctuation or variation in the tension in the strip may I be due to various causes, such as eccentricity of the coil of strip fed to the processing line. The peripheral speed increases as the diameter of the coil decreases. Fluctuation in the tension on the strip may cause severe shock and wear to the processing machinery. Vibrations may be produced which, especially when attaining resonating frequency, create pulsations which may be especially harmful to the equipment and likely to cause strip breakage.

Previous attempts to overcome the variation in tension and maintain a uniform tension throughout the processing line have included employment of a roll over which the strip passes, the roll being supported at each end by a piston rod connected with a piston operating in a cylinder, the location of the roll being controlled by air pressure against the pistons. When variations in strip tension occur the air under pressure in the cylinders cushions the linear roll movement and tends to inhibit or minimize variations in strip tension.

The procedure just described has limitations due to the operating characteristics of the pneumatic cylinders which are incapable of optimum response to the high frequency of tension variation of the elongated strip material in the processing line. Further, such procedure is not adopted for lines in which relatively substantial tension variation occurs.

I provide a tension controlling device which is capable of responding to high frequency fluctuations in tension and at the same time to relatively great variations in magnitude of tension and maintains relatively constant tension in the line. My tension controlling device absorbs tension when the tension in the processing line tends to increase and supplies tension to the line when the line tension tends to decrease, exerting substantially constant tension on the strip where-by to maintain substantially constant line tension.

I provide apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip by which the advancing strip is deflected from a straight line and which element is urged in one transverse direction by the advancing strip, together with means exerting a substantially constant force against said element opposite in direction to the force exerted thereon by the advancing strip whereby the strip tension is maintained relatively constant. The element bearing against the strip may be a rotatable roll with mounting means providing for its movement transversely of the direction of strip advance. The roll may underlie the strip and may deflect the strip upwardly from a straight line, being urged upwardly by the 3,227,347 Patented Jan. 4, 1966 substantially constant force while it is urged downwardly by the advancing strip. I preferably employ means acting on the element which bears against the strip urging that element toward the strip, such means including a turnable element and means applying a substantially constant torque to the turnable element in all positions thereof. Such means preferably include an electric motor.

The apparatus may and preferably does have means for back-tensioning the strip and means acting on the backtensioning means increasing the back tension on the strip when the strip tension tends to decrease and decreasing the back tension on the strip when the strip tension tends to increase. The means acting on the back-tensioning means are preferably actuated by turning of a turnable element such as above described. The means for backtensioning the strip may include an electric motor, and means including selsyn means may be provided acting on the electric motor causing it to increase the back tension on the strip when the strip tension tends to decrease and to decrease the back tension on the strip when the strip tension tends to increase. g

I further provide apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip and which is urged in one transverse direction by the advancing strip and means acting on said element urging it in the opposite transverse direction toward the advancing strip. Said means preferably include torsion means storing up energy imparted thereto through said element when the strip tension tends to increase and said element is moved in the first mentioned transverse direction and releasing said stored-up energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip tension. In such apparatus I preferably employ means applying a substantially constant torque to the torsion means in the direction opposite the direction of the torque applied to the torsion means by said element. The means applying the substantially constant torque to the torsion means preferably include an electric motor.

The locations on the torsion means where the respective oppositely directed torques are applied to the torsion means are spaced apart along the torsion means and means are preferably provided for altering the spacing therebetween whereby the operating characteristics of the torsion means may be controlled to meet various conditions of operation.

I further provide apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip, guide means for said element guiding the same in a path transversely of the path of the strip, the advancing strip urging said element in one direction in the guide means when the strip tension tends to increase, a torsion bar and connections between said element and the torsion bar twisting the torsion bar upon movement of said element in said direction in the guide means whereby the torsion bar stores up energy, the torsion bar untwisting to release stored up energy and urge said element in the opposite direction in the guide means toward the advancing strip when the strip tension tends to decrease to supplement the strip tension whereby the strip tension is maintained substantially constant. The connections between the element which bears against the advancing strip and the torsion bar may include rack means connected with that element and pinion means connected with the torsion bar in mesh with the rack means. The connection between said element and the torsion bar applies torque in one direction to the torsion bar upon movement of said element in said direction in the guide 3 means, and means are provided applying a substantially constant torque to the torsion bar in the opposite direction.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings I have shown a present preferred embodiment of the invention in which FIGURE 1 is a diagrammatic elevational view of a strip processing line embodying my invention;

FIGURE 2 is an elevational view to enlarged scale and in more detail than FIGURE 1 taken at the line 11-11 of FIGURE 1;

FIGURE 3 is a horizontal cross-sectional view taken on the line III-III of FIGURE 2;

FIGURE 4 is a vertical longitudinal cross-sectional view taken on the line IV-IV of FIGURE 2; and

FIGURE 5 is a partial elevational view of the structure shown in FIGURE 2 as viewed from the right hand end of that figure.

Referring now more particularly to the drawings, there is shown an uncoiler 12 adapted to carry a coil 14 of strip which for purposes of explanation and illustration will be considered to be steel strip to be treated in a continuous processing line. The strip is drawn from the coil and traverses a processing line designated generally by reference numeral 16 and is coiled up on a reel 17. In the processing line is a tension control unit designated generally by reference numeral 18. An electric motor is coupled to the uncoiler and acts thereon in the nature of a controllable brake to exert back tension on the strip, the tensioning effect of the motor 10 being controlled and determined by the current input to the motor.

The tension control unit 18 has a stationary support ing structure or frame 22. The strip 14 passes under a deflector roll 24, over a tension roll 26, then under a deflector roll 28. The rolls 24 and 28 are mounted in the stationary frame 22. The tension roll 26 has its bearings supported on each end by a bearing support 36 mounted in the frame 22 for vertical sliding movement so that the frame constitutes guide means therefor. Each bearing support 30 carries a downwardly extending rack 32. A shaft 36 extending transversely of the strip path is journaled in the frame 22 and has fixed thereto two pinions 34 respectively meshing with the racks 32.

One end of the shaft 36 has a coupling 40 to which is anchored a torsion bar 42 extending generally axially of the shaft 36. The torsion bar 42 passes through a hollow shaft 44 of reducer 46 having gearing for exerting torque on the shaft. The gearing is not shown in detail since the reducer except for the hollow shaft 44 may be conventional. A coupling 48 mounted on one end of the shaft 44 permits longitudinal passage of the torsion bar 42 but prevents rotational movement of the torsion bar with respect to the hollow shaft 44. The end 50 of the torsion bar 42 is rotatably supported at 49.

An electric motor 52 is coupled to the reducer 46 for exerting torque on the hollow shaft 44. Connections presently to be described are provided between the shaft 44 and the tension roll 26 through which an upward force is applied to the tension roll acting against the downward force applied to the tension roll by the strip to maintain the tension roll in substantial equilibrium. The motor 52 and reducer 46 are mounted on a base 54 slidably carried on ways 56 on a sub-base 58. A handwheel 60 operates an endless chain 62 which drives a screw 64 threaded through a nut 66 carried by the base 54. To vary the length of the torsion bar 42 between the couplings 40 and 48 the handwheel 69 is rotated which causes the screw 64 to turn and move the base 54 and the motor 52, reducer 46 and coupling 48 carried thereby along the sub-base 58 while the torsion bar 42 is maintained against endwise movement. Thereby the effective or twist length of the torsion bar may be controlled at will. The efiec tive or twist length of the torsion bar determines the de'" gree of twist of the torsion bar in response to a given force and is adjusted in accordance with operating cond1- tions, including strip gauge and width, coil weight, strip speed and line characteristics so that during operation the amplitude of movement of the tension roll 26 will be in a desired range.

A belt 63 couples a shaft 70 of the reducer 46 with a shaft '72 of a tachometer 74. A selsyn 76 is mechanically coupled to the tachometer 74 through reducer 78. The selsyn '76 produces a voltage which varies with the rotational position of the shaft 80. I

The strip 14 passing over the tension roller 26 exerts a downward force which through pinions 34 produces a torque in the shaft 36 which is coupled to the torsion bar 42 by the coupling 40. The motor 52 exerts through reducer 46 and coupling 48 a torque on torsion bar 42 in the rotational direction opposite that of the torque produced by the tension roller 26. This causes twisting of the torsion bar 42. Upon increase in the tension on the strip 14 the tension roll 26 is urged downwardly with consequent application of torque to the shaft 36 and hence to the torsion bar 42 twisting the torsion bar 42. The twisting of the torsion bar 42 allows slight downward movement of the tension roll 26 which reduces the tension on the strip. Thereupon the tension roll 26 will move upwardly accompanied by decrease in the twist of torsion bar 42. The energy stored up in the torsion bar 42 by the twisting thereof under strip tension is utilized to move the tension roll 26 upwardly when the strip ten sion decreases. Thus the torsion bar acts to damp fluc= tuations in strip tension and maintain the tension roll 26 in substantial equilibrium.

The torque induced in the torsion bar by the tension of the strip is opposed by torque induced in the torsion bar by the motor 52. The selsyn is electrically coupled to the motor 10 in such manner that it will increase or decrease the magnetomotive force within the motor 10 whereby the torque applied by the motor 10 to exert back tension on the strip 14 is correspondingly changed. The position of the tension roll 26 is a function of strip tension and torque output of the motor 52. With a constant torque applied to the motor 52 the position of the tension roll 26 is a direct function of strip tension. It is thus possible to regulate the tension in the strip by adjusting the torque output of the motor 10 of the uncoiler 12 in accordance with the position of the tension roll 26. For example, if the tension on the strip 14 increases the tension roll 26 will move downwardly. Such downward movement of the tension roll causes operation of the selsyn 76 to decrease the torque output of motor 10. When the tension on the strip decreases the result is the opposite; the tension roll 26 moves upwardly.- Such upward movement of the tension roll causes oper ation of the selsyn 76 to increase the torque output of motor 10. The result is continuous substantially uniform tension on the strip.

Primary tension in the strip is not determined by the tension control means but rather by current regulators operating on the coil holder motor. When factors tending to affect strip tension do not produce rapid or sudden changes in strip tension the torsion bar may not be subjected to substantial twist and the control mechanism will operate much as though the torsion bar were a rigid shaft. The primary importance of the torsion bar is to counteract instantaneous changes in strip tension due, for example, to pulsating effects caused by non-circular coils. The pulsating effects may be extremely rapid and the frequencies very high. Such pulsations are absorbed by the torsion bar and theoretically do not reach the armature of the motor 52. Thus, at low speeds the pul-' sating effect is small and with substantially circular coils In such a situation the pulsation is a minor problem. twist length of the torsion bar is shortened- When dealing with a coil having such eccentricity as to cause extreme pulsations the twist length of the torsion bar should be increased to allow the tension roll to absorb the greatest strip pulsations. Thus at times the tension control may be efiected without substantial twisting of the torsion bar, at other times the torsion bar may be the primary tension control element and at still other times both the torsion bar and the motor may participate in the control; indeed this is the normal situation.

While I have shown and described a present preferred embodiment of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

I claim:

1. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip, guide means for said element guiding the same in a path transversely of the path of the strip, the advancing strip urging said element in one direction in the guide means when the strip tension tends to increase, a torsion bar and connections between said element and the torsion bar including rack means connected with said element and pinion means connected with the torsion bar.

2. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip, guide means for said element guiding the same in a path transversely of the path of the strip, the advancing strip urging said element in one direction in the guide means when the strip tension tends to increase, a torsion bar, connections between said element and the torsion bar applying torque in one direction to the torsion bar upon movement of said element in said direction in the guide means and means applying a substantially constant torque to the torsion bar in the opposite direction.

3. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip by which the advancing strip is deflected from a straight line and which element is urged in one transverse direction by the advancing strip, and means acting on said element urging it in the opposite transverse direction toward the advancing strip, said means including a twistable torsion bar and means including an electric motor applying a substantially constant torque to said bar, said bar storing up energy imparted thereto through said element when the strip tension tends suddenly to increase and said element is moved in the first mentioned transverse direction and releasing said stored-up energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip tension, whereby the strip tension is maintained relatively constant.

4. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip by which the advancing strip is deflected from a straight line and which element is ur ed in one transverse direction by the advancing strip, and means acting on said element urging it in the opposite transverse direction toward the advancing strip, said means including a twistable torsion bar and means including an electric motor applying a substantially constant torque to said bar, said bar storing up energy imparted thereto through said element when the strip tension tends suddenly to increase and said element is moved in the first mentioned transverse direction and releasing said stored-up energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip tension, the locations along said bar of the connections therewith of said element and said electric motor being spaced apart in the direction of the length of the 6 bar, and means for altering the distance between said locations.

5. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip by which the advancing strip is deflected from a straight line and which element is urged in one transverse direction by the advancing strip, and means acting on said element urging it in the opposite transverse direction toward the advancing strip, said means including a twistable torsion bar and means including an electric motor applying a substantially constant torque to said bar, said bar storing up energy imparted thereto through said element when the strip tension tends suddenly to increase and said element is moved in the first mentioned transverse direction and releasing said stored-up energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip tension, the locations along said bar of the connections therewith of said element and said electric motor being spaced apart in the direction of the length of the bar, and means for altering the distance between said locations, the apparatus having means including a second electric motor for back-tensioning the strip and means including selsyn means actuated by turning of the bar acting on the second electric motor causing it to in crease the back tension on the strip when the strip tension tends to decrease and to decrease the back tension on the strip when the strip tension tends to increase.

6. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip and which is urged in one transverse direction by the advancing strip, means acting on said element urging it in the opposite transverse direction toward the advancing strip, said means including torsion means storing up energy imparted thereto through said element when the strip tension tends to increase and said element is moved in the first mentioned transverse direction and releasing said stored-up energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip tension, and means including an electric motor applying a substantially constant torque to the torsion means in the direction opposite the direction of the torque applied to the torsion means by said element, whereby the strip tension is maintained relatively constant.

7. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip and which is urged in one transverse direction by the advacing strip, means acting on said element urging it in the opposite transverse direction toward the advancing strip, said means including torsion means storing up energy imparted thereto through said element when the strip tension tends to increase and said element is moved in the first mentioned transverse direction and releasing said storedup energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip ten sion, means applying a substantially constant torque to the torsion means in the direction opposite the direction of the torque applied to the torsion means by said element, the locations on the torsion means where the respective oppositely directed torques are applied to the torsion means being spaced apart along the torsion means, and means for altering the spacing between said locations, whereby the strip tension is maintained relatively constant.

8. Apparatus for controlling the tension in a strip advancing continuously in a strip processing line comprising an element bearing against the advancing strip and which is urged in one transverse direction by the advancing strip, means acting on said element urging it in the opposite transverse direction toward the advancing strip, said means including torsion means storing up energy imparted thereto through said element when the strip tension tends to increase and said element is moved in the first mentioned transverse direction and releasing said stored-up energy to said element when the strip tension tends to decrease and said element is moved in the second mentioned transverse direction to supplement the strip tension, means including an electric motor applying a substantially constant torque to the torsion means in the direction opposite the direction or" the torque applied to the torsion means by said element, the locations on the torsion means where the respective oppositely directed torques are applied to the torsion means being spaced apart along the torsion means, and means for altering the spacing between said locations, whereby the strip tension is maintained relatively constant.

0 0 References Cited by the Examiner UNITED STATES PATENTS Re. 7,855 8/1877 Saladee 26757 1,265,328 5/1918 Henderson.

2,981,491 4/1961 Eans 318-6 X 3,143,950 8/1964 Elliott 242-75.5l X

OTHER REFERENCES Standard Handbook for Electrical Engineering, 6th edition, McGraw Hill'Book Co., 1933 (page 767 relied on).

M. HENSON WOOD, JR., Primary Examiner.

I. N. ERLICH, Assistant Examiner. 

1. APPARATUS FOR CONTROLLING THE TENSION IN A STRIP ADVANCING CONTINUOUSLY IN A STRIP PROCESSING LINE COMPRISING AN ELEMENT BEARING AGAINST THE ADVANCING STRIP, GUIDE MEANS FOR SAID ELEMENT GUIDING THE SAME IN A PATH TRANSVERSELY OF THE PATH OF THE STRIP, THE ADVANCING STRIP URGING SAID ELEMENT IN ONE DIRECTION IN THE GUIDE MEANS WHEN THE STRIP TENSION TENDS TO INCREASE, A TORSION BAR AND CONNECTIONS BETWEEN SAID ELEMENT AND THE TORSION BAR INCLUDING RACK MEANS CONNECTED WITH SAID ELEMENT AND PINION MEANS CONNECTED WITH THE TORSION BAR. 